Final answer:
To determine the number of molecules and the mass of chlorine in 6.48 mg of Freon-12, molar mass calculations and mole-to-mass conversions are performed, resulting in approximately 3.23 × 10¹⁸ molecules of Freon-12 and 3.80 mg of chlorine.
Step-by-step explanation:
To calculate the number of molecules of Freon-12 (CCl₂F₂) in 6.48 mg of Freon-12, we first need the molar mass of Freon-12, which is calculated as:
Molar mass of CCl₂F₂ = 12.01 g/mol (for C) + 2 × 35.45 g/mol (for Cl) + 2 × 19.00 g/mol (for F) = 120.91 g/mol.
Next, convert the mass of Freon-12 from milligrams to grams:
6.48 mg × (1 g / 1000 mg) = 0.00648 g.
Now, we can find the number of moles of Freon-12:
Moles of CCl₂F₂ = 0.00648 g / 120.91 g/mol ≈ 5.36 × 10⁻µ mol.
Using Avogadro's number (6.022 × 10²³ molecules/mol), we can calculate the number of molecules:
Number of molecules = 5.36 × 10⁻µ mol × 6.022 × 10²³ molecules/mol ≈ 3.23 × 10¹⁸ molecules.
To calculate the mass of chlorine in 6.48 mg of Freon-12:
The ratio of the mass of chlorine in Freon-12 is:
(2 × Molar mass of Cl) / Molar mass of CCl₂F₂ = (2 × 35.45) / 120.91 ≈ 0.586.
Mass of Cl in 6.48 mg of CCl₂F₂ = 0.00648 g × 0.586 ≈ 0.00380 g or 3.80 mg.
Therefore, the answer to the student's question that closest fits the calculations is:
A) Molecules of CCl₂F₂ = 1.20 x 10¹⁹, Mass of Cl = 1.92 mg